Carpet Calculator - Area, Cost and Material Estimator
Enter your room dimensions, carpet price per square yard or foot, padding cost, and labour rate to instantly see total area, yardage to order (with waste), and a full cost breakdown. Supports metric and imperial units, up to three rooms, stair coverage, and five common waste-factor presets.
How to measure for carpet
Measure each room as a simple rectangle: length times width in feet gives square footage. For L-shaped rooms, split the space into two rectangles and add the areas together. Doorways and closets are usually included - installers prefer not to cut around every little alcove. Stairs are calculated separately: multiply the number of steps by the stair width, then by 2 feet (the combined riser and tread depth of a standard step). Always measure in feet and convert to square yards for ordering, because carpet is sold by the square yard.
Why waste factor matters
Carpet comes on rolls that are typically 12 feet wide. If your room is 14 feet wide you need two strips, and the second strip wastes nearly the full width. A standard 10% waste allowance covers simple rectangular rooms with straight cuts. Go up to 12-15% for L-shaped rooms and any carpet with a repeating pattern - the pattern must align across seams, which can waste 15 inches or more per join. Stairs need 15-20% because each step is cut individually with no efficient way to reuse offcuts. Berber (loop pile) can get away with 8% because it has no directional pile. When in doubt, round up: leftover carpet is useful for repairs; running short forces an expensive re-order.
Understanding carpet cost per square yard
Carpet retail pricing is quoted per square yard in the United States. A budget polyester costs around $5-$12 per square yard for the material alone. Mid-grade nylon runs $9-$20, and high-end wool can reach $40-$60. Padding (underlay) adds $3-$8 per square yard but dramatically affects how the carpet feels and how long it lasts - never skip it. Installer labour typically costs $3-$8 per square yard and includes removing old carpet, tack-strip installation, and stretching. Expect a total installed cost of $10-$30 per square yard for most residential projects. Some retailers advertise low per-yard prices but charge separately for removal, furniture moving, and transitions - get a line-item quote.
Carpet padding: what to choose
Padding is the hidden layer that makes the biggest single difference to carpet comfort and longevity. The Carpet and Rug Institute recommends a 7/16-inch maximum thickness with a density of 6 pounds per cubic foot for most residential carpet. Thicker or softer padding can feel luxurious but causes the carpet to flex excessively, which wears out the backing faster. Rebond foam (the multicoloured recycled variety) is the most popular choice and the best value. Memory foam padding is more expensive and not always recommended by manufacturers. Fibre pads suit Berber and loop-pile carpet better than foam because they provide a firmer base that prevents stretching at the seams.
Metric vs. imperial: ordering carpet outside the US
In Canada and Australia carpet is commonly sold by the square metre or linear metre. UK retailers may quote per square metre or per square yard. If your retailer quotes per square metre, divide the square yard price by 1.196 to compare. This calculator shows area in all three units (sq ft, sq yd, m²) so you can copy the right number straight onto your order form, regardless of which unit the store uses.
Carpet material comparison
| Fibre | Price range (per sq yd) | Lifespan | Best for | Stain resistance |
|---|---|---|---|---|
| Polyester (PET) | $5 - $15 | 8-12 years | Bedrooms, low traffic | Good |
| Olefin (Polypropylene) | $5 - $12 | 5-8 years | Basements, outdoors | Excellent |
| Nylon | $9 - $25 | 12-15 years | High traffic, stairs | Very good |
| Berber/Loop pile | $8 - $20 | 15-20 years | Offices, hallways | Fair |
| Triexta (SmartStrand) | $10 - $22 | 10-15 years | Family rooms, pets | Excellent |
| Wool | $20 - $60 | 20-25 years | Luxury rooms | Fair |
Typical price ranges and performance characteristics for common carpet fibres.
Frequently asked questions
How do I convert square feet to square yards for carpet?
Divide the area in square feet by 9. There are 9 square feet in one square yard. For example, a room that is 12 ft x 10 ft = 120 sq ft, which is 120 / 9 = 13.33 sq yd. Always add your waste percentage before ordering.
How much waste should I add when buying carpet?
Add 10% for simple rectangular rooms, 12-15% for L-shaped or irregular rooms, and 15-20% for patterned carpet or stairs. The pattern repeat dictates the true waste - a 24-inch repeat on a 12-ft roll can waste a full yard per seam.
Is padding included in the carpet price?
Not always. Many retailers quote the carpet material price only. Padding (underlay) is usually sold separately, often at $3-$8 per square yard. Always confirm whether a quote includes padding before comparing prices.
How is stair carpet measured?
Multiply the number of steps by the stair width and by 2 feet (the combined riser and tread depth of a typical step). For example, 14 steps, 3 ft wide: 14 x 3 x 2 = 84 sq ft. Add 15-20% waste because each step is cut separately with minimal reuse of offcuts.
What is the average cost to carpet a room?
A typical 12 x 10 ft bedroom (13.3 sq yd) with mid-grade nylon carpet at $14/sq yd, standard padding at $4/sq yd, and installation at $5/sq yd comes to roughly $310 fully installed, or about $2.30 per sq ft. Costs vary widely by region, carpet grade, and whether old carpet removal is included.
Can I install carpet without underlay (padding)?
Technically yes, but it is not recommended. Carpet without padding wears out 30-50% faster because the backing flexes against the hard floor with every step. Manufacturers often void the warranty if carpet is installed without a suitable pad. The cost of padding is small relative to its impact on feel and lifespan.